Plum pox

Sharka ( plum pox or disease) is one of the plum pox virus (English: plum pox virus ( PPV) ) caused plant disease of stone fruit. It affects especially plums / prunes and peaches / nectarines and apricots and is the most important disease that has spread to Germany since the 1960s and now occurs throughout the country.

Due to the disease, in particular the commercial cultivation of plums / prunes by revenue decline and poor fruit quality is affected.

Sharka virus

When causative agent of Sharka is a filamentous, 20 × 764 nanometers ( ) ssRNA virus of the genus potyvirus, of the four strains (D, M, C and EA ) are known. The individual virus strains exhibit various forms of symptoms and also vary in the choice of host plants. The detection of the 750 -nm long agent can be effected by ELISA or the PCR method.

Symptoms

Infection with the plum pox virus leads to various symptoms, their strength depending on the variety can vary in strength. On leaves of plums / prunes (May / June) are formed in the spring hellolivgrüne to olive rings, which can develop black spots of dead tissue. Depressions that are pocked or linear and where the flesh takes on a reddish color and rubbery consistency (up to the stone ) form on the fruit. As a result of the infection can lead to a strong, early fall of fruit.

Especially with heat and dryness, during the vegetation period, the symptoms most frequently and significantly.

Origin and transmission

The problems caused by this virus symptoms were first observed in 1917 in Bulgaria, Dimitar Atanasov from 1933 Sharka was also first described and recognized as a viral disease. Meanwhile Sharka is found in almost all of Europe.

As a carrier (vector ) function at short distances aphids (especially green peach aphid, Large Zwetschgenblattlaus, Green Zwetschgenblattlaus and hop aphid ) that have taken up the pathogen in an infected tree. For longer distances, the spread is done by finishing with infected veins or documents.

Combat

The plum pox virus and the caused of this symptoms of Sharka disease can not be fought directly.

Only the spread can be prevented / reduced by:

• Combat insect-borne
• Clearance of infected plants
• Use of virus-free documents and Reiser
• Use little virus susceptible / resistant cultivars and rootstocks

Due to the Scharkaverordnung a clearing and destruction of infected plants by the competent authorities can be arranged.

In the cultivation of stone fruit in infested areas, the only way is to choose varieties suitable for cultivation.

Currently trying to breed Sharka resistant plums / prunes varieties. The first (and so far only ) completely Sharka resistant variety the variety ' Jojo ' was in 1981 at the University of Hohenheim bred.

Compulsory registration

According to the " Regulation on the control of Scharkakrankheit " subject to the reporting requirement of the disease, further are further regulated control measures.

Scharka-Anfälligkeit/-Toleranz/-Resistenz

The different varieties of stone fruit species are - depending on their individual, genetically determined, resistance - different vulnerable to the Sharka disease. There are

• Susceptible varieties - the tree shows strong symptoms is severely damaged and the fruits are not marketable. In part to the degree of susceptibility (also depending on the environmental factors such as, for example, drought) are differentiated herein. eg: house plum, Fellberg

• Eg: Hanita, Katinka, Tophit plus, Cacaks Beautiful, Best Cacaks etc.

• Eg: Jojo